Suicide clusters are described as of two main types: Mass clusters (media-related phenomena where suicides occur during a restricted time period) and Point clusters ( an unusually high number of suicides occur in a small geographical area or institution and over a relatively brief period of time). Third type of cluster is also described : Geographical but not temporal clustering of suicides.(Eg: suicides on the London Underground system and suicides at or near railway stations which are adjacent to psychiatric units).
Camilla Haw, Keith Hawton, Claire Niedzwiedz and Steve Platt review literature on Point Clusters in this article. They included 46 papers which generally covered characteristics of members of the cluster, environmental risk factors and psychological mechanisms .
Clusters are thought to account for 1% to 2% of all suicides occurring during adolescence. They are more common among males(as suicide in general). Individuals involved generally have negative self-esteem, are socially isolated and tend to internalize feelings and conflicts.
Clusters in inpatients: Departure of, or changes to, senior clinical staff is a significant trigger. Influx of new staff, including new junior doctors,weak leadership,uncertainty about the future of the hospital are other risk factors described.
Mechanisms: Copycat suicides following a celebrity suicide is more likely if media coverage is extensive and the suicide glamorized or reported it in detail. Dose-response relationship is seen between regional newspaper distribution and the size of this imitative suicide effect.Werther effect ( wave of suicide following publication in 1774 of Goethe’s novel, The Sorrows of Young Werther), a result of imitation, is reported by many studies.
Contagion, a concept from infectious diseases, is increasingly applied in cluster suicides.Those who are part of an at-risk population and have geographical and psychosocial proximity to a suicide are particularly vulnerable.
Imitation and suggestion,projective identification,pathological identification, learning and priming are mechanisms used to explain clusters.
Social integration levels, homophily (the tendency of individuals with certain characteristics to preferentially associate with one another), assortative susceptibility (individuals vulnerable to suicide belong to particular strata in society) are the alternative concepts used to explain suicide clusters.
Adolescents and young adults are at greatest risk of being involved in clusters of suicides. Changes in inpatient staff is a significant risk factor for clusters in these units. Several contagion mechanisms and alternatives (like homophily) are described.There is limited scientific evidence to support the operation of any of these mechanisms in cluster formation.
Summary of the article:
Suicide clusters: a review of risk factors and mechanisms. Haw C, Hawton K, Niedzwiedz C, Platt S. Suicide Life Threat Behav. 2013 Feb;43(1):97-108